Traditionally, radio frequency identifier (RFID) systems with an IC tag for RFID and a reader/writer (hereinafter simply referred to as a “reader device”) include:
(1) a communication system that makes use of signals in the ultra-high frequency (UHF) band (for example, signals in the 920 MHz band or the 2.45 GHz band) (hereinafter referred to as the “UHF system”) (see, for example, Patent Document 1); and
(2) a communication system that makes use of signals in the high frequency (HF) band (for example, signals in the 13.5 MHz band) (hereinafter referred to as the “HF system”) (see, for example, Patent Document 2).
The UHF system performs communication by making use of an IC tag with an antenna, such as a dipole antenna, a slot antenna, or the like, and by utilizing electromagnetic waves (electrical waves). As compared to the HF system, the UHF system can send a large amount of information by utilizing the characteristic to the effect that the communication distance is large (in the order of a few meters), and it is often used in systems where data transmission and reception with respect to multiple IC tags are performed all at once.
In particular, since the UHF system has such characteristic, it is often used in systems where simultaneous communication with a plurality of terminal units is performed more than once, such as physical distribution management systems, rather than in systems where one-on-one individual communication is necessary, and it provides convenience in such communication systems.
On the other hand, the HF system performs communication by making use of an IC tag with a loop-coil type antenna and by utilizing electromagnetic waves (magnetic field resonance). As represented by near field communication (NFC), the HF system is often used in systems where the communication distance is small, in the order of a few centimeters to a few tens of centimeters, due to the access range constraint under magnetic field strength. In particular, since the HF system has such characteristic, it provides convenience in one-on-one communication, i.e. individual communication.
It should be noted that, in either system, the IC tag contains no power supply for operations in order to achieve miniaturization, light weight and low cost of IC tags. The IC tags of a type (i.e. a passive type) are mainly utilized, in which a power supply for operations is secured by generating an electromotive force based on the electric waves transmitted from a reader device.